It has been already known in the art to apply an anion exchange resin as the so called anticholesteremic which promotes a reduction of cholesterol levels in the blood (U.S. Pat. Nos. 3,499,960 and 3,780,171; U.K. Pat. No. 929,391; and Japanese Unexamined Patent Publication No. 10386/1978). The mechanism in which cholesterol levels in the blood are reduced may be considered as follows. That is, a basic anion exchange resin immobilizes through adsorption bile acids existing in the intestinal tract to prevent bile acids from being absorbed again, whereby conversion of cholesterol in equilibrium relations with bile acids to bile acids is promoted to result in reduction of cholesterol levels in the blood.
In the prior art, a typical example of a basic anion exchange resin used as anticholesteremic is an ion-exchange resin having an aliphatic quaternary ammonium salt as the functional group (U.S. Pat. Nos. 3,499,960 and 3,780,171). This ion-exchange resin having an aliphatic quaternary ammonium salt as the functional group can be produced by allowing an aliphatic tertiary amine to react with a haloalkyl introduced onto a crosslinked polymer, but the resultant anion exchange resin is accompanied with an objectionable odor inherent in an aliphatic amine and therefore cannot be put into practical uses as such. Thus, in practical applications, a coating is applied on the surface of the anion exchange resin to alleviate the bad odor, but the dosage is obliged to be increased due to the reduction in ion-exchange capacity as the result of the surface coating. Also, such an anion exchange resin of the prior art is low in selective adsorption of bile acids and has the drawback that useful substances such as vitamins are also removed by adsorption.
The present inventors have already invented, as a resin having improved the drawbacks as mentioned above, a polystyrene type anion exchange resin having imidazolium group as the functional group which has a high selective adsorption capacity for bile acids (Japanese Unexamined Patent Publication No. 150017/1981).
On the other hand, along the thought that an anticholesteremic composed principally of an anion exchange resin can be more effective through adsorption of not only bile acids existing in the intestinal tract but also of cholesterol, investigations have been made intensively about a resin having high selective adsorption capacity for bile acids and having further enhanced cholesterol adsorption capacity. As a consequence, this invention has been accomplished.
That is, an object of this invention is to provide a basic anion exchange resin which is free from a bad odor and has selective adsorption capacity for bile acids and cholesterol, and it concerns an anticholesteremic principally composed of an epoxy type anion exchange resin having animidazolium salt in the main chain as the functional group.